Ventilator



FIG. 1 is a front view of a ventilator according to our new ornamental design;

FIG. 2 is a rear view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a right side view thereof; and,

FIG. 5 is a left side view thereof.

The broken line showing of portions of a ventilator is included for the purposes of illustrating environmental structure and forms no part of the claimed design. 

CLAIM The ornamental design for a ventilator, as shown and described. 